Use of superhydrophobic surfaces for liquid agglutination assays

Abstract

This invention relates to the use of thermodynamically incompatible surfaces in agglutination assays for the express purpose of using the sample as a key component of the detection instrument. Specifically, the invention relates to formation of a lense and a virtual container for rapid mixing via thermal energy by a sample liquid disposed on a superhydrophobic surfaces, and a subsequent specific analyte or overall protein concentration assay using particles agglutination for use in the industrial, environmental, and clinical laboratory test fields.

What is claimed is: 
     
       1. A method for determining the presence of a protein in an aqueous liquid biological sample, comprising:
 a. depositing a droplet of the aqueous liquid biological sample on a surface consisting of a superhydrophobic material, wherein all portions of the surface are superhydrophobic, that is thermodynamically incompatible with the bulk liquid of the aqueous liquid sample, wherein said droplet forms a liquid lens having a contact angle with the superhydrophobic surface of no less than about 150°; 
 b. depositing nanoparticles onto the surface of the droplet of the aqueous liquid biological sample, wherein said nanoparticles are capable of aggregating in the presence of said protein; 
 c. exposing the liquid lens to focused light from a light source in parallel with a surface of said lens; and 
 d. measuring a time-dependent change in intensity of the focused light, relative to an initial intensity; 
 wherein a change in light intensity indicates the presence of said protein. 
 
     
     
       2. The method of  claim 1 , wherein said nanoparticles are selected from the group consisting of gold, silver and latex nanoparticles. 
     
     
       3. The method of  claim 1 , wherein said nanoparticles have a diameter of between about 20 nm and about 300 nm. 
     
     
       4. The method of  claim 1 , wherein said nanoparticles are silver nanoparticles having a diameter of about 20 nm. 
     
     
       5. The method of  claim 1 , wherein said intensity of the light is measured for a period of about 10 seconds to about 30 seconds. 
     
     
       6. The method of  claim 1 , wherein the aqueous liquid biological sample is blood, plasma, serum, gastrointestinal secretions, homogenates of tissues or tumors, synovial fluid, feces, urine, saliva, sputum, cyst fluid, amniotic fluid, cerebrospinal fluid, peritoneal fluid, lung lavage fluid, semen, lymphatic fluid, tears, prostatic fluid, or a combination thereof. 
     
     
       7. The method of  claim 1 , wherein the superhydrophobic surface is coated with a material selected from the group consisting of silicone compounds, silanes, fluorocarbon polymers, perfluoroalkyl ethyl methacrylate (PPFEMA) coated polycaprolactone, hydrocarbons, polymer mats made of polystyrene and poly[tetrafluoroethylene-co-(vinylidene fluoride)-co-propylene] (PTVFP), polyethylene glycol with glucose and sucrose in conjunction with a superhydrophobic substance, combinations of nanoparticles with polyethylene or polypropylene; high density polyethylene, technical waxes, films of rough particles of metal oxides, polymer binder layers containing a plurality of porous protrusions, and a combination thereof. 
     
     
       8. The method of  claim 1 , wherein the light source is a source of UV light, visual light, NIR light, IR light, or a combination thereof. 
     
     
       9. The method of  claim 1 , wherein said superhydrophobic surface comprises a hold, defect, post, or depression in order to rigidly hold the aqueous liquid sample in place. 
     
     
       10. The method of  claim 1 , wherein the light source is a light emitting diode (LED). 
     
     
       11. The method of  claim 1 , further comprising positioning a detector at a focal point colinear to the light source. 
     
     
       12. The method of  claim 1 , wherein the presence of said protein is detected when:
 i) the measured time-dependant change in intensity is a time-dependant increase in intensity, relative to the initial intensity, where the initial intensity is measured when the nanoparticles are deposited onto the surface of the droplet; or 
 ii) the measured time-dependant change in intensity is a time-dependant decrease in intensity, relative to the initial intensity, where the initial intensity is measured a few seconds after the nanoparticles are deposited onto the surface of the droplet. 
 
     
     
       13. A method for determining the presence of a protein in an organic solvent, comprising:
 a. depositing the organic solvent on a superoleophobic surface, wherein all portions of the superoleophobic surface are thermodynamically incompatible with the bulk liquid of the organic solvent, wherein said organic solvent forms a liquid lens having a static organic solvent contact angle with the superoleophobic surface of more than about 120°; 
 b. depositing a drop of nanoparticles onto the surface of the organic solvent, wherein said nanoparticles are capable of aggregating in the presence of said protein; 
 c. exposing the liquid lens to focused light from a light source in parallel with the surface of said lens; and 
 d. measuring a time-dependent change in intensity of the focused light, relative to an initial intensity; 
 wherein a change in light intensity indicates the presence of said protein. 
 
     
     
       14. A method for determining the presence of an analyte in a liquid biological sample, comprising:
 a. contacting the liquid biological sample with a binding substance specific to the analyte sought to be determined, said binding substance being immobilized on a nanoparticle or microparticle; 
 b. depositing the liquid biological sample with the binding substance on a surface that is thermodynamically incompatible with the bulk liquid of the biological sample wherein said liquid biological sample forms a bead having a contact angle with the thermodynamically incompatible surface of no less than about 150°; 
 c. exposing the liquid biological sample with the binding substance to focused light from a light source in parallel with the surface; and 
 d. measuring a time-dependent change in light intensity, relative to an initial intensity, wherein a change in light intensity indicates the presence of the analyte, 
 wherein all portions of the surface are thermodynamically incompatible with the bulk liquid of the biological sample. 
 
     
     
       15. The method of  claim 14 , wherein said nanoparticle or microparticle has a known size or size distribution. 
     
     
       16. The method of  claim 14 , wherein the surface is superhydrophobic. 
     
     
       17. The method of  claim 14 , wherein the liquid biological sample is aqueous. 
     
     
       18. The method of  claim 14 , wherein the liquid biological sample is blood, plasma, serum, gastrointestinal secretions, homogenates of tissues or tumors, synovial fluid, feces, urine, saliva, sputum, cyst fluid, amniotic fluid, cerebrospinal fluid, peritoneal fluid, lung lavage fluid, semen, lymphatic fluid, tears, prostatic fluid, or a combination thereof. 
     
     
       19. The method of  claim 14 , wherein the binding substance is an antibody specific against the analyte. 
     
     
       20. The method of  claim 19 , wherein the antibody is a monoclonal antibody. 
     
     
       21. The method of  claim 14 , wherein the binding substance is a ligand specific against the analyte. 
     
     
       22. The method of  claim 14 , wherein the binding substance is a polynucleotide specific against the analyte. 
     
     
       23. The method of  claim 14 , wherein the surface is coated with a material selected from the group consisting of silicone compounds, silanes, fluorocarbon polymers, perfluoroalkyl ethyl methacrylate (PPFEMA) coated polycaprolactone, hydrocarbons, polymer mats made of polystyrene and poly[tetrafluoroethylene-co-(vinylidene fluoride)-co-propylene] (PTVFP), polyethylene glycol with glucose and sucrose in conjunction with a hydrophobic substance, combinations of nanoparticles with polyethylene or polypropylene; high density polyethylene, technical waxes, films of rough particles of metal oxides, polymer binder layers containing a plurality of porous protrusions, and combinations thereof. 
     
     
       24. The method of  claim 14 , wherein the surface is a metallo-organic compound, metal, treated glass, clay or a combination thereof. 
     
     
       25. The method of  claim 14 , wherein the light source is a source of UV light, visual light, NIR light, IR light, or a combination thereof. 
     
     
       26. The method of  claim 25 , wherein the wavelength is about the same diameter as the nanoparticle or microparticle. 
     
     
       27. The method of  claim 14 , wherein the step of measuring the change in light intensity further comprises measuring an increase in forward light scatter, relative to an initial light scatter, as a function of time; and
 wherein the step of measuring the increase in forward light scatter is preceded by a step of depositing another portion of the same liquid biological sample on the thermodynamically incompatible surface with the same nanoparticle or microparticle in the absence of the binding substance. 
 
     
     
       28. The method of  claim 27 , wherein the step of measuring the increase in forward light scatter as a function of time comprises comparing the changes in light scattering between said liquid biological sample contacted with said binding substance and said another portion of the same liquid biological sample. 
     
     
       29. The method of  claim 14 , wherein:
 the liquid biological sample comprises a bodily fluid or a tissue sample from a patient; 
 the analyte is characteristic of an infectious disease; and 
 said change in light intensity indicates the presence of the infectious disease in the patient. 
 
     
     
       30. The method of  claim 14 , wherein the light source is a light emitting diode (LED). 
     
     
       31. The method of  claim 14 , further comprising positioning a detector at a focal point colinear to the light source.